From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] iommu/amd: Only unmap large pages from the first pte Date: Sun, 23 Jun 2013 14:00:25 +0200 Message-ID: <20130623120020.GB2557@8bytes.org> References: <20130621203242.7475.19737.stgit@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20130621203242.7475.19737.stgit-xdHQ/5r00wBBDLzU/O5InQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Alex Williamson Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Fri, Jun 21, 2013 at 02:33:19PM -0600, Alex Williamson wrote: > If we use a large mapping, the expectation is that only unmaps from > the first pte in the superpage are supported. Unmaps from offsets > into the superpage should fail (ie. return zero sized unmap). In the > current code, unmapping from an offset clears the size of the full > mapping starting from an offset. For instance, if we map a 16k > physically contiguous range at IOVA 0x0 with a large page, then > attempt to unmap 4k at offset 12k, 4 ptes are cleared (12k - 28k) and > the unmap returns 16k unmapped. This potentially incorrectly clears > valid mappings and confuses drivers like VFIO that use the unmap size > to release pinned pages. > > Fix by refusing to unmap from offsets into the page. > > Signed-off-by: Alex Williamson > Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Applied, thanks for fixing this.